Circuit breaker employing sickle shaped contact, engaging stationary contact and impulse grid



Oct. 29. 1957 P. L. TAYLOR CIRCUIT BREAKER EMPLOYING SICKLE SHAPED CONTACT, ENGAGING STATIONARY CONTACT AND IMPULSE GRID 3 Sheets-Sheet 1 Filed Nov. 3, 1953 mom/veg P. L. TAYLOR 2,811,614 CIRCUIT BREAKER EMPLOYING SICKLE SHAPED CONTACT, ENGAGING Oct. 29. 1957 STATIONARY CONTACT AND IMPULSE GRID 3 SheetsSheet 2 Filed NOV. 3, 1953 mm M,

Oct. 29, 1957 p TAYLOR 2,811,634

CIRCUIT BREAKER EMPLOYING SICKLE SHAPED CONTACT, ENGAGING STATIONARY CONTACT AND IMPULSE GRID Filed Nov. 3, 1953 3 Sheets-Sheet 3 United States Patent CIRQUET BREAKER EMPLOYING SICKLE SHAPED CtDNTACT, ENGAGING TATIONARY CONTACT AND IMPULSE GRID Phiiip L. Taylor, deceased, late of Abington, Mass., by Dorothy S. Taylor, administratrix, Abington, Mass., assignor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis.

Application November 3, 1953, Serial No. 389,953

9 Claims. (Cl. 200-150) This invention relates to electric circuit interrupters and more particularly to are extinguishing structures therefor.

More specifically this invention relates to a novel structure for effecting the very rapid initiation, elongation and extinction of electric arcs drawn in circuit interrupters. This invention is applicable to the interruption of high voltage arcs such as those drawn in 287 kv. circuit but is also applicable on low voltage circuits. Heretofore by increasing the circuit interrupting ability of a given type of circuit breaker, the overall size of the structure increased. lviodern industry now demands increased in terrupting ability of its circuit breakers with a decrease in the size of the overall structures.

Experience has demonstrated that a rapid lowering of the dieiectric strength of an arc extinguishing fluid, such as oil, occurs after it impinges upon the arc stream. It is therefore desirable to eliminate such contaminated fluid as quickly as possible, and to subject the arc stream to the action of fresh fluid of high dielectric strength. The isolation or disconnection of a capacitance load by a circuit breaker in an alternating current system is sub ject to transient overvoltages, the magnitudes of which depend on the capacitance of the load, the voltage of the system, and the type of the circuit breaker. In isolating such a capacitance load, interruption at the first current zero in the arc of the leading current is readily effected at a relatively small contact separation. In onehalf cycle after the first current zero, the voltage of the source has reversed to its crest value, and approximately double this voltage appears across the circuit breaker contacts as a circuit recovery voltage. Whether or not restriking of the arc occurs depends on several factors, such as the type of the circuit breaker, including the speed and the magnitude of the separation of its contacts, the magnitude of the circuit recovery voltage, and the leading kva. of the load.

These circuit conditions are difficult if not impossible to control. Therefore, restriking in most breakers must be expected especially under severe operating conditions, and the circuit interrupting structures must operate efiiciently under such conditions.

In accordance with this invention a new and improved circuit interrupting structure is provided in which an arc interrupter is immersed in arc extinguishing fluid. The interrupter comprises a stationary contact having at least two segments biased together to form a tubular member. The segments are grooved to form a dual purpose chamber extending into the tubular member from one end thereof and a slot extending into the tubular member from the other end thereof. The chamber and slot form contact surfaces for engaging movable contacts. One of the movable contacts comprising a sickle shaped mem ber pivotally mounted at a point between the ends thereof is provided with a first arcing contact mounted at one end of the sickle shaped member and is arranged for engaging the contact surfaces of the chamber when in circuit closed position and to draw a first are between the first arcing contact and the contact surfaces of the chamber when moved to circuit open position. The other or second movable arcing contact is of a bayonet shape and is arranged to engage the contact surfaces of the slot when in circuit closed position and to draw a second are between the bayonet shaped movable contact and the contact surfaces of the slot when moved to circuit open position. The chamber forms a pressure generating enclosure for bathing the arcing contact surfaces thereof in fluid and for creating a surge of fluid over the first arcing contact of the sickle shaped member when a first arc is drawn between the first arcing contact and the contact surfaces of the chamber. An arc extingushing device comprising a plurality of spaced parallelly arranged barrier plates is arranged adjacent the chamber for cooling and extinguishing the are drawn between the first arcing contacts of the sickle shaped member and the contact surfaces of the chamber.

The are extinguishing device defines a first passageway extending from the chamber through the barrier plates for the sickle shaped contact member and the arcing con tact mounted thereon, and a second passage extending through the barrier plates transversely of the first passageway. A piston is provided for causing a flow of fluid under pressure through the second passage of the arc extinguishing device upon movement of the sickle shaped member to contact open position to cool and extinguish the first arc. Means are provided to actuate the bayonet shaped contact to draw a second are substantially simultaneously with the first arc to interrupt the electric circuit.

It is, therefore, one object of the present invention to provide a new and improved circuit breaker structure for establishing, lengthening and extinguishing an arc.

Another object of this invention is to provide a new and improved dual purpose stationary contact structure and cooperating movable contact are extinguishing structure in which the configuration of the stationary contact makes it possible to reduce the circuit breakers overall s1ze.

A further object of this invention is to provide a new and improved circuit breaker structure in which an improved construction adapted for use with a cooperating pairof movable contacts causes an arc extinguishing blast of fluid to flow across one of the arcing contacts to aid the arc extinguishing action of the structure.

Objects and advantages other than those set forth wiil be apparent from the following description when read in connection with the accompanying drawings, in which:

Fig. 1 is an elevational view partly in section of a circuit interrupter embodying the invention and shown in circuit closed position;

Fig. 2 is an enlarged sectional View through one of the interrupting devices shown in Fig. 1;

Fig. 3 is an enlarged sectional view of the stationary contact structure shown in Fig. 2;

Fig. 4 is a top view of the contact structure shown in Fig. 3;

Fig. 5 is an elevational view of the upper disk assembly shown in Fig. 2;

Fig. 6 is a top view of the disk assembly shown in Fig. 5;

Figs. 7 to 11 are detailed views of the disks forming the assembly shown in Figs. 5 and 6; and

Fig. 12 is an enlarged cross sectional view taken along the line XiL-XH of Fig. 2.

Referring to the drawings by characters of reference, Fig. 1 illustrates an oil circuit breaker unit of the high voltage type such as that used in power transmission systems. Unit 1 is suspended from one line terminal of the circuit interrupter in a suitable tank 2 and submerged in a suitable insulating arc extinguishing fluid, such as oil. A conducting bridging bar 3 serves to connect electrically the arc extinguishing unit 1 with an identical unit 4 in a manner well known in the art. Supported on a cover 5 of the tank 2 are a pair of terminal bushings 6 and 7 (partially shown), to the lower ends of which are secured arc extinguishing units 1 and 4. The cross bar 3 is actuated reciprocally in the vertical direction by an insulating lift rod 8 to open and close the contacts of the arc extinguishing units 1 and 4.

Fig. 2 is an enlarged view in cross section of the left hand are extinguishing structure shown in Fig. 1. The right hand are extinguishing structure is of similar design. In Fig. 2 the interrupting chamber 9 contains interrupting and pressure generating arcing contacts 10, 11 and 12, of which the movable contact is mounted at one end of a sickle shaped member 13 pivotally mounted at a point 14 between the ends thereof. Point 14 is arranged above contact 11.

As shown in Fig. 4 the stationary contact structure 11 comprises a plurality of segments 16 usually two in number biased together by spring means to provide a tubular or cylindrical tulip type contact member. Spring means 15 provide a loose pivotal mounting for each segment. The upper end of each segment of contact structure 11 is grooved to form a rectangular slot or chamber 17 forming a pressure generating enclosure extending into structure 11 from the top end thereof substantially coaxially with the longitudinal axis of member 11. The lower end of each segment forming structure 11 is grooved to form a cylindrical recess or slot 18 extending into structure 11 from the lower end thereof substantially coaxially with the longitudinal axis of structure 11. The slot walls 19 and 20 of slots 17 and 18, respectively, form contact surfaces which engage contacts 10 and 12 when in contact closed position.

Arcing contact 10 cooperates with the contact surface or walls 19 of the slot or chamber 17 to produce a first arc, and the bayonet contact 12 and particularly arcing tip 80 thereof cooperates with the contact surfaces or walls 20 of slot 18 to produce a second arc. A perforated insulating plate 24 serves as the lower mounting for the contact. An insulating tube 25 holds an impulse grid structure 42 and the tulip shaped contact structure 11 in coaxial relationship in the interrupting chamber 9. Frame means 21 are provided for independently mounting the arcuate segments 16 for limited freedom of movement.

Each segment 16 may be so disposed that whenthe breaker is moved into contact closed position the contact surfaces 19 and 20 of the slots 17 and 18, respectively, engage the opposing contact surfaces of the contacts 10 and 12 with a wiping action. If the contacts 10 and 12 move slightly out of their usual path, the arcuate segments will still move into engagement with contacts 10 and 12 to provide a tight electrical connection.

Chamber 17 is provided in member 11 to serve a dual purpose. First, the walls of chamber 17 provide contact engaging surfaces which engage contact 10 when in closed circuit position, and secondly chamber 17 forms a pressure generating enclosure for bathing the arcing contacts in fluid and upon the drawing of an are between arcing contact 10 and the contact surfaces of walls 19 of chamber 17 creating a surge of fluid from chamber 17 over the arcing contact 10 and sickle member 13 and the contact engaging walls 19 of chamber 17 to cool the surfaces thereof and to aid in extinguishing the arc therebetween.

Contacts 10, 11 and 12 are separated upon the downward movement of an insulating stud or push rod 26. A spring 27 upon the downward movement of push rod 26 and of bridging contact3 and operating rod 8 in contact opening direction rapidly accelerates sickle shaped member 13 andinterrupting arcing contact 10 in contact opening direction. The sickle shaped member 13 is attached at 28 to a pair of drag links 29. Links 29 are pivotally mounted by pin 30 on a metallic cap 32 fastened to insulating push rod 26. The metallic caps 32 may be slotted to form a bifurcated portion and links 29 and sickle shaped member 13 are arranged in the slot. The upper end of spring 27 rests against a fixed shoulder 31 of the frame structure of the interrupting chamber 9.

The circuit breaker structure shown in Fig. 2 may employ spring actuated interrupting contacts such as contacts 10, 11, alone or in combination with spring actuated oil pumps for the interruption of line charging currents and such low value of inductive currents as are not efiectively interrupted by suicidal type devices.

Push rod 26 at its end remote from the bridging contact member 3 abuts against a push rod 34. Push rod 34 is provided with a valve stem 35 and a spring biased valve element 36 forming a part of a spring biased piston 37. Piston 37 is arranged in a cylinder 38 of a pump 39. Cylinder 38 is openat its lower end so that oil ahead of piston 37 will be forced through the lower open end of cylinder 38 into the pressure or interrupting chamher 9.

During a circuit closing operation of the interrupter,

the bridging contact member 3 forces the push rod 26 upward. Push rod 26 in its upward movement rotates sickle shaped member 13 and arcing contact 10 counterclockwise to cause contact 10 to engage the slot wall sides 19 of its fixed contact structure 11. Push rod 26 in its upward movement to closed circuit position pushes rod 34 upward against the biasing action of the spring biased piston 37'. The electrical circuit through this are interrupting chamber 9 comprises lead-in conductor (not shown) arranged in the bushing 6, the support and the walls of chamber 9, flexible connector 41, sickle shaped member 13, movable interrupting contact 10, fixed interrupting contact 11, movable arcing contact 12, and bridging contact member 3.

The are interrupting unit 1 utilizes two groups of parallelly arranged barrier plate assemblies 42 and 43 of suitably shaped insulating plates which form part of the walls of the paths through which the arcs produced by contacts 10, 11 and 12 are drawn.

Each interrupting unit is provided with two parallel cylindrical resistor assemblies 45. The upper end of each resistor assembly 45 is conductively connected to an electrostatic shield 46. Shield 46 is conductively connected to housing 44 which in turn is conductively connected to the lower terminal end of the breaker bushing 6. The lower end of each resistor assembly 45 is conductively connected to the lower electrostatic shield 47. Shield 47 is conductively connected to an arcing electrode comprising a disk like member 48 through a conductive circuit comprising bolts 49, plate 50, bolts 51 and ring support 52.

The lower end of unit 1 is provided with an insulating nozzle 55 forming a fluid opening 56. The arcing electrode 48 is secured Within unit 1 between the lower end of the barrier plate assembly 43 and the blast opening 56.

When it is desired to open the electric circuit passing through the interrupter, or when overload conditions exist in the electric circuit controlled by the interrupter, suitable operating mechanism (not shown) moves the insulating lift rod 8 to result in a downward movement of the conducting crossbar 3 and the movable contacts 12, 12.

The downward movement of cross bar 3 causes insulating operating rod 26 to rotate sickle shaped member 13 and contact 10 clockwise about the pivot stud 14 to draw an arc between contacts 10 and 11. Substantially simultaneously therewith or with a slight delay, the movable bayonet shaped contact 12 separates from the intermediate or fixed contact 11 to draw an arc between contacts 11 and 12. The downward movement of operating rod 26 permits the downward movement of spring biased piston 37 to move the oil within the pump cylinder 38. The oil, now under pressure withinthe pump cylinder 38, flows under pressure out of the cylinder 38, chamber 9 and through a passage of the barrier plate stack 42 extending transversely of the longitudinal axis of the arc extinguishing unit 1.

If it is desirable to isolate the oil and gas flow between barrier plate assemblies 42 and 43, the oil and gas passing through barrier plate stack 42 is exhausted through a chamber 57 and exhaust port 58 to the inside of tank 2, otherwise the port 58 is closed with a pipe plug 59 so that the oil and gas flow through assembly 42 will pass through assembly 43.

Assembly 42 as shown in Figs. 5 to 11, inclusive, is arranged to direct the oil under pressure from the cylinder 38 through a flow passageway 61, a plurality of nozzles or flow passages 62 arranged to direct substantially all of the fluid passing through passageway 61 across an arc passageway 63 laterally thereof, through connecting exhaust passageways 64 extending transversely of the longitudinal axis of the assembly 42 and of the flow passages 62 into exhaust passages 65 extending parallel with the longitudinal axis of the assembly 42. Exhaust passages 65 direct the oil under pressure past the intermediate contact 11 and into the barrier plate assembly 43.

The flow passageways 61, flow passages 62, are passageway 63, connecting exhaust passageway 64, and exhaust passageways 65 are formed by disks 68 to 72 which are shown respectively in Figs. 7 to 11. Disks 69 and 71 have substantially butterfly shaped cutout portions extending from the central aperture forming a part of the contact or are passageway 63 with the openings into the flow passageway 61 and the venting connecting passageways 64 (more clearly shown in Fig. 6). Disks 70 illustrate the connecting and exhaust passageways 64 which connect the flow passages 62 of disks 71 with the exhaust passages 65.

To clarify the disclosure as to the passages and passageways, the disks in Fig. 5 are numbered to illustrate the sequence used in assembly 42. Each disk has four small apertures through which the fastening members 75 extend and hold the assembly disks in proper relation. As shown in Fig. 5, the disks 70 and 71 are alternated through part of the stack assembly 42 so that a plurality of spaced flow passages or nozzles 62 force jets of oil across the arc passageway 63.

Fig. 5 illustrates the preferred form of the present in vention, in which the passages 62 are spaced apart the thickness of one plate or disk 70. However, other sequences of disk arrangements such as a sequence using two disks 70 and one disk 71 or two disks 71 and one disk 70 to form the spaced nozzles 62 may be used and are intended to fall within the scope of this invention.

The grid assembly 42 is particularly useful in circuit breakers used to isolate a capacitive load of such capacitance and voltage that the voltage gradient across the are interrupting contacts of the circuit breaker exceeds the dielectric strength between these contacts.

Upon the separation of contact 10 from the arcing wall surfaces 19 of chamber 17, an arc is produced which creates a pressure in chamber 17 resulting in a surge of fluid from chamber 17 over arcing contact 10, sickle shaped member 13 and contact surfaces 19 of chamber 17. This surge of fluid cools the contact surfaces and the are created therebetween. The surge of fluid under pressure is created by the expansion of the arc gases immediately surrounding the arc. These gases create a pressure in chamber 17 which pressure forces the fluid such as oil in chamber 17 out of a nozzle 22 in chamber 17 and into the spaced barrier plate assembly 42 through contact passageway 63. Device or assembly 42 provides passageway 63 for sickle shaped contact 13 and arcing contact 10 to extend from the slot or chamber 17 through the assembly 42.

During the interruption of low currents, the operating rod 26 moves downwardly at the same speed as the cross bar 3 to result in the sickle shaped member 13 and contact 10 rotating clockwise about stud 14 to draw an arc to inspect or repair.

between contacts 10 and 11. The rod 34 and piston 37 follow the downward movement of operating rod 26. Valve element 36 closes and moves the oil in cylinder 38 into interrupting chamber 9. This action occurs during the interruption of low currents.

During the interruption of high current arcs, the pressure created by the are drawn between contacts 10 and 11 may prevent the downward movement of the piston 37 and this, in turn, halts the downward movement of the rod 34. Push rod 34 then separates from rod 26 at surface 33 on push rod 34.

As the pressure subsides within the barrier plate assembly 42 at or near zero of the alternating current wave oil under pressure within chamber 9 flows out through barrier plate assembly 42 to flush the region where the arc occurred between contacts 10 and 11. This scavenging action raises the dielectric strength of the oil in the barrier plate assembly 42 and prevents restriking between contacts 1% and 11 which would prolong the arcing time of the interrupter. It also prevents premature breakdown of the contact gap during and immediately following closing operation. The grid assembly 42 is particularly useful in circuit breakers used to isolate a capacitive load of such capacitance and voltage that the voltage gradient across the arc interrupting contacts of the circuit breaker exceeds the dielectric strength between these contacts.

The downward movement of contact 12 draws an arc in the barrier plate stack assembly 43 between contact 12 and the fixed contact 11. The are drawn between contacts 11 and 12 breaks down a portion of the arc extinguishing liquid which surrounds the arc and saturates the barrier plate assembly 43. The barrier plate assembly 43 may be of the type shown and claimed in U. S. Patent No. 2,467,542, Philip L. Taylor, April 19, 1949. This type of barrier plate assembly provides helical passages which produce a helical flow of liquid through the barrier plates and a contact passageway 6% formed therein.

The flow of oil under pressure through barrier plate assembly 42 is directed around the intermediate contact structure 11 and into the contact passageway 60 where it is acted upon by the barrier plate assembly 43 to produce the helical liquid flow to extinguish the interrupting are established in barrier plate assembly 43.

While the circuit breaker is opening, an arcing surface 8t) of the movable contact 12 passes the arcing electrode 48 before passing through nozzle 55. Part of contact 12 moves through the nozzle during interruption of the power arc. Immediately after momentary interruption at a current zero, the returning voltage between contacts 10 and 11 and 11 and 12 causes current to flow through the resistor assembly 45 because the voltage breaks down the gap at one or more points on the surface of arcing electrode 43 (due to the short gap between the electrode 43 and the body of contact 12 as compared with the main interrupting gap between surface 86 and contact 11). The resistor assembly 45 is thereby inserted in series with the power circuit through an auxiliary arc so that the resistance circuit now shunts the contacts 10, 11 and 12.

The magnitude of the arc current is correspondingly decreased by the resistance and the difiiculty of completely interrupting the current is greatly diminished, particularly in the case of circuits having high rates of increase of the recovery voltage and also in the case of capacitance switching. The ohmic value of the resistance 45 depends on the characteristics of the circuit to be controlled.

\Vhen the comparatively weak arc current through the resistor is finally extinguished by the cooling effect of the oil, further downward movement of contact 12 serves to increase the oil gap for isolating the contacts from each other so that there is no danger of flashover or restriking of the arc.

Thus, an eflicient, simple and compact interrupting unit is provided that occupies less space within the oil tank than conventional interrupting chambers and that is easy The resistor unit can be readily removed from the breaker and replaced independently of the chamber and the contacts therein so that complete disassembly of the chamber construction is unnecessary.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In a circuit interrupter immersed in arc extinguishing fluid, a stationary contact comprising a. plurality of segments biased together to form a tubular member, said segments being grooved to form a first slot extending into said tubular member from one end thereof and a second slot extending into said tubular member from the other end thereof, said slots forming contact surfaces for en gaging movable contacts, a first sickle shaped member pivotally mounted at a point between the ends thereof, an arcing contact mounted at one end of said sickle shaped member for cooperating with the contact surfaces of said first slot for providing a first are, a second movable contact cooperating with the contact surfaces of said second slot for producing a second arc, and an arc extinguishing device comprsiing a plurality of parallelly arranged barrier plates for cooling and extinguishing said first arc, said device defining a passageway extending from said first slot through said device for said sickle shaped contact member and said arcing contact.

2. In a circuit interrupter immersed in arc extinguishing fluid, a stationary contact comprising a plurality of segments biased together to form a tubular member, said segments being grooved to form a first slot extending into said tubular member from one end thereof and a second slot extending into said tubular member from the other end thereof, said slots forming contact surfaces for engaging movable contacts, a first sickle shaped member pivotally mounted at a point between the ends thereof, an arcing contact mounted at one end of said sickle shaped member for cooperating with the contact surfaces of said first slot for producing a first are, a second movable contact cooperating with the contact surfaces of said second slot for producing a second arc, an arc extinguishing device comprising a plurality of spaced parallelly arranged barrier plates for cooling and extinguishing said first are, said device defining a passageway extending from said first slot through said device for said sickle shaped contact member and said arcing contact, and a piston actuated upon movement of said sickle shaped member for causing a flow of fluid between said spaced barrier plates for cooling and extinguishing said first are.

3. In a circuit interrupter immersed in arc extinguishing fluid, a stationary contact comprising a plurality of segments biased together to form a tubular member, said segments being grooved to form a first slot extending into said tubular member from one end thereof and a second slot extending into said tubular member from the other end thereof, said slots forming contact surfaces for engaging movable contacts, a first sickle shaped member pivotally mounted at a point between the ends thereof, an arcing contact mounted at one end of said sickle shaped member for engaging the contact surfaces of said first slot, a second movable contact cooperating with the contact surfaces of said second slot to produce a second are, an arc extinguishing device comprising a plurality of parallelly arranged barrier plates for cooling and extinguishing said first arc, said device defining a first passageway extending from said first slot through said device for said sickle shaped contact member and said arcing contact, and a second passage extending through said barrier plates transversely of said first passageway, means for moving said sickle shaped contact member and said arcing contact through said first passageway of said device to extend a first are, a piston for causing a flow of fiuid under pressure through said second passage of said device tot cool and extinguish said first arc, and means for actuating said second movable contact to draw a second arc.

4. In a circuit interrupter immersed in arc extinguishing fluid, a stationary contact comprising two segments biased together to form a tubular member, said segments being grooved to form a dual purpose chamber extending into said tubular member from one end thereof and a slot extending into said tubular member from the other end thereof, said chamber and slot forrnling contact surfaces for engaging movable contacts, a first sickle shaped member pivotally mounted at a point between the ends thereof, an arcing contact mounted at one end of said sickle shaped member for cooperating with the contact surfaces of said chamber to produce a first arc, said chamber forming a pressure generating enclosure for bathing said arcing contact in fluid and for creating a surge of fluid from said chamber over said arcing contact upon creation of an are between said arcing contact and said contact surfaces of said chamber, a second movable contact cooperating with the contact surfaces of said slot to produce a second arc, and an are extinguishing device comprising a plurality of parallelly arranged barrier plates for cooling and extinguishing said first are, said device defining a passageway extending from said chamber throughsaid device for said sickle shaped contact member and said arcing contact.

5. In a circuit interrupter immersed in arc extinguishing fluid, a stationary contact comprising two segments biased together to form a tubular member, said segments being grooved to form a dual purpose chamber extending into said tubular member from one end thereof and a slot extending into said tubular member from the other end thereof, said chamber and slot forming contact surfaces for engaging movable contacts, a first sickle shaped member pivotally mounted at a point between the ends thereof, a first arcing contact mounted at one end of said sickle shaped member for engaging the contact surfaces of said chamber, said chamber forming a pressure generating enclosure for bathing said first arcing contact 'in fluid and for creating a surge of fluid over said first arcing contact upon creation of an are between saidfirst arcing contact and said contact surfaces of said chamber, a second movable arcing contact cooperating with the contact surfaces of said slot to produce a second arc, and an arc extinguishing device comprising a plurality of parallelly arranged barrier plates for cooling and extinguishing said first arc, said device defining a first passageway extending from said chamber through said device for saidsickle shaped contact member and said first arcing contact, and a second passage extending through said barrier plates transversely of said first passageway, means for moving said sickleshaped contact member and said first arcing contact through said first passageway of said device to extend a first are, a piston for causing a flow of fluid under pressure through said second passage of said device to cool and extinguish said first arc, and means for actuating said second movable arcing contact to draw a second are.

6. In a circuit interrupter immersed in arc extinguish.- ing fiuid, a stationary contact comprising two segments biased together to form a tubular member, said segments. being grooved to form a. dual purpose chamber extending into said tubular member from one end thereof. and a slot, extending into said tubular member from the other end thereof, said chamber andtsaid slot forming contact surfaces for engaging movable contacts, a first sickle shaped member'pivotally mounted at a point between the ends thereof, a first arcing contact mounted at one end of said sickle shaped member for engaging the con tact surfaces of said chamber, a second movable arcing contact cooperatingwith the'contact surfaces of said. slot to produce a second'arc, and anarc extinguishingdevice comprising a plurality off parallelly arranged barrier device defining a first passageway extending from said chamber through said device for said sickle shaped contact member and said first arcing contact, and a second passage extending through said barrier plates transversely of said first passageway, means for moving said sickle shaped contact member and said first arcing contact through said first passageway of said device to extend said first arc, a piston for causing a flow of fluid under pressure through said second passage of said device, said chamber forming a pressure generating enclosure for bathing said first arcing contact in fluid and for creating a surge of fiuid over said first arcing contact and through said first passageway upon creation of said first arc, and means for actuating said second movable arcing contact to draw a second arc.

7. In a circuit interrupter immersed in arc extinguishing fluid, a stationary contact comprising a plurality of segments biased together to form a cylindrical contact member, said segments being grooved to form a rectangular slot extending into said member from one end thereof substantially coaxially with its longitudinal axis and a cylindrical slot extending into said member from the other end thereof substantially longitudinally of said axis, said rectangular slot forming a contact surface for engaging a sickle shaped contact and said cylindrical slot forming a contact surface for engaging a bayonet shaped contact, a sickle shaped member pivotally mounted at a point, between the ends thereof, an arcing contact mounted at one end of said sickle shaped member for engaging the contact surfaces of said rectangular slot to produce a first are, :a movable bayonet shaped contact cooperating with the contact surfaces of said cylindrical shaped slot to produce a second arc, and an arc extinguishing device comprising a plurality of parallelly arranged barrier plates for cooling and extinguishing said first are, said device defining a passageway extending from said rectangular slot through said device for said sickle shaped contact member and said arcing contact.

8. In a circuit interrupter immersed in arc extinguishing fluid, a stationary contact comprising a plurality of segments biased together to form a cylindrical contact member, said segments being grooved to form a dual purpose chamber extending into said member from one end thereof substantially coaxially with its longitudinal axis and a cylindrical slot extending into said member from the other end thereof substantially longitudinally of said axis, said chamber forming a contact surface for engaging a sickle shaped contact and said cylindrical slot forming a contact surface for engaging a bayonet shaped contact, a sickle shaped member pivotally mounted at a point between the ends thereof, an arcing contact mounted at one end of said sickle shaped member for engaging the contact surfaces of said chamber to produce a first arc, a movable bayonet shaped contact cooperating with the contact surfaces of said cylindrical shaped slot to produce a second are, said chamber forming a pressure gencrating enclosure for bathing said arcing contact in fluid and for creating a surge of fluid over said arcing contact upon creation of an are between said arcing contact and said contact surfaces of said chamber, and an arc extinguishing device comprising a plurality of parallelly arranged barrier plates for cooling and extinguishing said first arc, said device defining a passageway extending from said chamber through said device for said sickle shaped contact member and said arcing contact.

9. In a circuit interrupter immersed in arc extinguishing fluid, a stationary contact comprising two segments biased together to form a cylindrical contact member, said segments being grooved to form a dual purpose chamber extending into said member from one end thereof substantially coaxially with its longitudinal axis and a cylindrical slot extending into said member from the other end thereof substantially longitudinally of said axis, said chamber forming a contact surface for engaging a sickle shaped contact and said cylindrical slot forming a contact surface for engaging a bayonet shaped contact, a sickle shaped member pivotally mounted at a point between the ends thereof, an arcing contact mounted at one end of said sickle shaped member for engaging the contact surfaces of said chamber to produce a first arc, a movable bayonet shaped contact cooperating with the contact surfaces of said cylindrical shaped slot to produce a second arc, an arc extinguishing device comprising a plurality of parallelly arranged barrier plates for cooling and extinguishing said first are, said device defining a first passageway extending from said chamber through said device for said sickle shaped contact member and said arcing contact, and a second passage extending through said barrier plates transversely of said first passageway, means for moving said sickle shaped contact member and said arcing contact through said first passageway of said device to extend said first arc, said chamber forming a pressure generating enclosure for bathing said arcing contact in fluid and for creating a surge of fluid over said arcing contact and through said first passageway upon creation of an arc between said arcing contact and said contact surfaces of said chamber, a piston for causing a flow of fluid under pressure through said second passage of said device to cool and extinguish said first arc, and means for actuating said bayonet shaped contact to draw a second arc.

References Cited in the file of this patent UNITED STATES PATENTS 2,545,334 Balentine Mar. 13, 1951 2,600,211 Cushing June 10, 1952 2,621,273 Friedrich et a1 Dec. 9, 1952 2,695,349 Baker et a1. Nov. 23, 1954 FOREIGN PATENTS 719,244 Germany Apr. 2, 1942 

